Erect much-branched, shrub-like perennial, up to 2 m high. Branches often 4-angled, covered with short hairs and long hairs at the nodes. Leaves lanceolate to ovate with bristly hairs on both surfaces, 2-5 veined from the base. Flowers terminal in groups of 1-3, and solitary in the upper leaf axils, mauve-pink to purple. Stamens in 2 forms, shorter ones yellow, longer ones with curved purple anthers.